The present invention relates to heat dissipating devices, and particularly to a heat dissipating device having slanting engaged heat dissipating sheets and a bottom plate.
With the advance of integrated circuit (IC) technology, CPUs are made more and more compact and has higher operation speed than old ones. Thereby, a great deal of heat is generated. However in current trend, it is desired that the electronic devices have compact size, that is, they are smaller, and thus, it is required that the heat dissipating devices of the electronic devices are compact and has powerful heat dissipating ability.
With reference to FIGS. 1A and 1B, an assembled schematic view and a partial enlarged cross section view of a prior art IC heat dissipating device are illustrated. In that heat dissipating device, a plurality of recesses 11 are formed on a surface of a substrate 1. Each two recesses 61 are formed with a rib 12. There are a plurality of fins 2. Two sides of the lower end of the fin 2 are formed with respective extending portions 21. Thereby, the fin 2 can be inserted into the recess 11 (referring to FIG. 1A). Two side walls of the ribs 12 are punched by a plurality of punching weights so that the walls are expanded outwards to clamp the extending portions 2. Thereby, the fins 2 are firmly secured to the substrate 1 (referring to FIG. 1B), and thus an IC heat dissipating device is formed.
Although above said structure can be used, in punching the ribs, only the top end of the ribs 12 deform. The gaps are formed at lower ends between recesses 11 and the heat dissipating fins 2. If this heat dissipating device is placed on an IC. Heat will transfer to the substrate and thus to the heat dissipating fine 2. The heat can not be transferred to the whole fins 2 since the gaps at the lower ends between the recesses 11 and the heat dissipating fins 2.
Referring to FIG. 2, a schematic perspective view of another prior art IC heat dissipating device is illustrated. In FIG. 2, the substrate 3 is formed with a plurality of recesses 31. The heat dissipating fins 4 are placed in the recesses 31. A plurality of punching weights 41 punch the recesses 31 so that the wall of the recesses 31 deform and thus the heat dissipating fins 4 are clamped in the recesses tightly. Thereby, the assembly of the heat dissipating device is finished. However since a front end of the plurality of punching weights 41 are reduced to have a thinner end so that the punching weights 41 are drawn out easily. The pressure applied to the connection of the lower end of the recesses 31 and the heat dissipating fins 4 of heat dissipating device is sufficient. Thereby, gaps are generated at that place. Heat of the substrate 3 can not be sufficiently transferred to the heat dissipating fins 4 quickly. Thereby, the contact areas between the heat dissipating fins 4 and the recesses 31 are smaller so that the heat dissipating effect is not preferred.
Accordingly, the primary object of the present invention is to provide a heat dissipating device which comprises a bottom plate and plurality of heat dissipating sheets. A surface of the bottom plate is formed with a plurality of inclined recesses which are spaced with an equal space. Each inclined recess is inclined to a surface of the bottom plate and has two parallel sides, and every two adjacent recesses are spaced by a respective protruding rib. One end of each heat dissipating sheet has an inclined extending portion which has two parallel sides and is inclined to other portion of the heat dissipating sheet. The extending portions are inserted into the recesses of the bottom plate. By above structure, the heat dissipating sheets are inserted into the recesses of the bottom plate.
Another object of the present invention is to provide a heat dissipating device with slanting engaged heat dissipating sheets and a bottom plate, wherein the materials of the bottom plate and heat dissipating sheets are selected from one of copper and aluminum.